1 /* 2 * Some low level IO code, and hacks for various block layer limitations 3 * 4 * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com> 5 * Copyright 2012 Google, Inc. 6 */ 7 8 #include "bcache.h" 9 #include "bset.h" 10 #include "debug.h" 11 12 #include <linux/blkdev.h> 13 14 /* Bios with headers */ 15 16 void bch_bbio_free(struct bio *bio, struct cache_set *c) 17 { 18 struct bbio *b = container_of(bio, struct bbio, bio); 19 mempool_free(b, c->bio_meta); 20 } 21 22 struct bio *bch_bbio_alloc(struct cache_set *c) 23 { 24 struct bbio *b = mempool_alloc(c->bio_meta, GFP_NOIO); 25 struct bio *bio = &b->bio; 26 27 bio_init(bio); 28 bio->bi_max_vecs = bucket_pages(c); 29 bio->bi_io_vec = bio->bi_inline_vecs; 30 31 return bio; 32 } 33 34 void __bch_submit_bbio(struct bio *bio, struct cache_set *c) 35 { 36 struct bbio *b = container_of(bio, struct bbio, bio); 37 38 bio->bi_iter.bi_sector = PTR_OFFSET(&b->key, 0); 39 bio->bi_bdev = PTR_CACHE(c, &b->key, 0)->bdev; 40 41 b->submit_time_us = local_clock_us(); 42 closure_bio_submit(bio, bio->bi_private); 43 } 44 45 void bch_submit_bbio(struct bio *bio, struct cache_set *c, 46 struct bkey *k, unsigned ptr) 47 { 48 struct bbio *b = container_of(bio, struct bbio, bio); 49 bch_bkey_copy_single_ptr(&b->key, k, ptr); 50 __bch_submit_bbio(bio, c); 51 } 52 53 /* IO errors */ 54 55 void bch_count_io_errors(struct cache *ca, int error, const char *m) 56 { 57 /* 58 * The halflife of an error is: 59 * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh 60 */ 61 62 if (ca->set->error_decay) { 63 unsigned count = atomic_inc_return(&ca->io_count); 64 65 while (count > ca->set->error_decay) { 66 unsigned errors; 67 unsigned old = count; 68 unsigned new = count - ca->set->error_decay; 69 70 /* 71 * First we subtract refresh from count; each time we 72 * succesfully do so, we rescale the errors once: 73 */ 74 75 count = atomic_cmpxchg(&ca->io_count, old, new); 76 77 if (count == old) { 78 count = new; 79 80 errors = atomic_read(&ca->io_errors); 81 do { 82 old = errors; 83 new = ((uint64_t) errors * 127) / 128; 84 errors = atomic_cmpxchg(&ca->io_errors, 85 old, new); 86 } while (old != errors); 87 } 88 } 89 } 90 91 if (error) { 92 char buf[BDEVNAME_SIZE]; 93 unsigned errors = atomic_add_return(1 << IO_ERROR_SHIFT, 94 &ca->io_errors); 95 errors >>= IO_ERROR_SHIFT; 96 97 if (errors < ca->set->error_limit) 98 pr_err("%s: IO error on %s, recovering", 99 bdevname(ca->bdev, buf), m); 100 else 101 bch_cache_set_error(ca->set, 102 "%s: too many IO errors %s", 103 bdevname(ca->bdev, buf), m); 104 } 105 } 106 107 void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio, 108 int error, const char *m) 109 { 110 struct bbio *b = container_of(bio, struct bbio, bio); 111 struct cache *ca = PTR_CACHE(c, &b->key, 0); 112 113 unsigned threshold = op_is_write(bio_op(bio)) 114 ? c->congested_write_threshold_us 115 : c->congested_read_threshold_us; 116 117 if (threshold) { 118 unsigned t = local_clock_us(); 119 120 int us = t - b->submit_time_us; 121 int congested = atomic_read(&c->congested); 122 123 if (us > (int) threshold) { 124 int ms = us / 1024; 125 c->congested_last_us = t; 126 127 ms = min(ms, CONGESTED_MAX + congested); 128 atomic_sub(ms, &c->congested); 129 } else if (congested < 0) 130 atomic_inc(&c->congested); 131 } 132 133 bch_count_io_errors(ca, error, m); 134 } 135 136 void bch_bbio_endio(struct cache_set *c, struct bio *bio, 137 int error, const char *m) 138 { 139 struct closure *cl = bio->bi_private; 140 141 bch_bbio_count_io_errors(c, bio, error, m); 142 bio_put(bio); 143 closure_put(cl); 144 } 145